The Alexandria false antechinus (Pseudantechinus mimulus), also known as the Carpentarian false antechinus or Carpentarian pseudantechinus, is a small carnivorous marsupial, found only in a number of small, isolated localities in northern Australia. It is the smallest and rarest of the false antechinuses.[3]

The Alexandria false antechinus has had a long history of confusion with the fat-tailed false antechinus (P. macdonnellensis) ever since it was first described by Oldfield Thomas in 1906. W.D.L. Ride suppressed the species in 1971, placing it with the fat-tailed false antechinus, but it was restored by D.J. Kitchener in 1991. Its scientific name means "little mimic of false-antechinus".[5]

The Alexandria false antechinus is coloured buff brown above and greyish white below. Its main distinguishing feature from other false antechinuses is its small size.[5] The behaviour of this species has not been described.[3]

The P. mimulus is endemic to Australia. More specifically they are restricted to Sir Edward Pellew Group (Northern Territory), Centre and Southwest Islands, and two locations near Queensland. In the 1988 census of the territories the species was found in the Centre and South West Islands, but in the 2003 census it was not located. It is believed that the P. mimulus still resides within that area, but is yet to be confirmed.[7] In addition, the habitat in which the species resides in is a rocky one with scattered trees and wood.[4]

The Alexandria false antechinus has a very limited distribution, which has resulted in its classification by the IUCN as endangered. On the offshore islands it inhabits, it is fairly common; however, it is rare and, in 1995, had not been seen on the mainland since 1905, when it was discovered.[5]